Corrected command for updateassemblyinfo

As per here:

https://github.com/ParticularLabs/GitVersion/wiki/Command-Line-Tool#directly-on-build-server

```
/updateassemblyinfo
```

By itself, won't work.  Since there is now an expectation that there will be a parameter passed in, either indicating that it should happen, i.e. **true** or providing a relative or absolute path to a CommonAssemblyInfo file
Merge pull request #39 from gep13/patch-1

Corrected command for updateassemblyinfo